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Abstract:

Methods and systems for providing crosstalk compensation in a jack are
disclosed. According to one method, the crosstalk compensation is adapted
to compensate for undesired crosstalk generated at a capacitive coupling
located at a plug inserted within the jack. The method includes
positioning a first capacitive coupling a first time delay away from the
capacitive coupling of the plug, the first capacitive coupling having a
greater magnitude and an opposite polarity as compared to the capacitive
coupling of the plug. The method also includes positioning a second
capacitive coupling at a second time delay from the first capacitive
coupling, the second time delay corresponding to an average time delay
that optimizes near end crosstalk. The second capacitive coupling has
generally the same overall magnitude but an opposite polarity as compared
to the first capacitive coupling, and includes two capacitive elements
spaced at different time delays from the first capacitive coupling.

Claims:

1. A method for providing crosstalk compensation in a jack, the crosstalk
compensation being adapted to compensate for undesired crosstalk
generated at a capacitive coupling located at a plug inserted within the
jack, the method comprising: positioning a first capacitive coupling
between first and second wire pairs of the jack at a first time delay
away from the capacitive coupling of the plug; positioning a second
capacitive coupling including at least first and second capacitive
elements between the first and second wire pairs at a second time delay
from the first capacitive coupling, wherein the second time delay
corresponding to an average time delay that optimizes near end crosstalk,
and wherein different time delays of the first and second capacitive
elements in the second capacitive coupling are centered about the average
time delay to optimize near end crosstalk and are spaced apart to
compensate for far end crosstalk.

2. The method of claim 1, wherein the first capacitive coupling has a
greater magnitude and an opposite polarity as compared to the capacitive
coupling of the plug.

3. The method of claim 2, wherein the second capacitive coupling has
generally the same overall magnitude but an opposite polarity to the
first capacitive coupling.

4. The method of claim 1, further comprising providing a third capacitive
coupling positioned a third time delay away from the second capacitive
coupling, such that the third time delay is approximately the same as the
first time delay.

5. The method of claim 4, wherein the third capacitive coupling has
approximately the same overall magnitude but an opposite polarity to the
capacitive coupling located at the plug inserted within the jack.

6. The method of claim 1, wherein the first capacitive coupling includes
at least two capacitive elements, wherein the at least two capacitive
elements of the first capacitive coupling vary in magnitude, thereby
reducing alien crosstalk generated by the plug and jack.

7. The method of claim 1, wherein the first and second wire pairs
comprise the 3-6 and 4-5 wire pairs within an RJ-45 jack.

8. The method of claim 1, wherein the first and second capacitive
elements in the second capacitive coupling have differing magnitudes.

9. A telecommunications jack for use in a twisted pair system, the jack
comprising: a plurality of contact springs adapted to make electrical
contact with a plug when the plug is inserted into the jack; a plurality
of wire termination contacts for terminating wires to the jack; a
crosstalk compensation arrangement that provides crosstalk compensation
between elected tracks extending between the contact springs and the wire
termination contacts, the crosstalk compensation arrangement including a
first zone of compensation a first time delay away from the capacitive
coupling of the plug and a second zone of compensation at a second time
delay from the first zone of compensation, the second zone of
compensation including two capacitive elements spaced at different time
delays from the first zone of compensation to optimize far end crosstalk
and having an average time delay that optimizes near end crosstalk.

10. The telecommunications jack of claim 9, further comprising a third
capacitive coupling positioned a third time delay away from the second
capacitive coupling, such that the third time delay is approximately the
same as the first time delay.

11. The telecommunications jack of claim 10, wherein the third capacitive
coupling has approximately the same overall magnitude but an opposite
polarity to the capacitive coupling located at the plug inserted within
the jack.

12. The telecommunications jack of claim 9, wherein the first capacitive
coupling includes at least two capacitive elements, wherein the at least
two capacitive elements of the first capacitive coupling vary in
magnitude, thereby reducing alien crosstalk generated by the plug and
jack.

13. The telecommunications jack of claim 9, wherein the first zone of
compensation has a greater magnitude and an opposite polarity as compared
to the capacitive coupling of the plug, and the second zone of
compensation has generally the same overall magnitude but an opposite
polarity as compared to the first zone of compensation.

14. The telecommunications jack of claim 9, wherein the second zone of
compensation is positioned such that the second time delay is greater
than the first time delay.

15. The telecommunications jack of claim 9, wherein the first and second
zones of compensation are placed across the 3-6 and 4-5 wire pairs within
the jack.

16. A method for providing crosstalk compensation in a jack, the
crosstalk compensation being adapted to compensate for undesired
crosstalk generated at a capacitive coupling located at a plug inserted
within the jack, the method comprising: positioning a first capacitive
coupling between first and second wire pairs of the jack at a first time
delay away from the capacitive coupling of the plug, the first capacitive
coupling including at least two capacitive elements, wherein the at least
two capacitive elements of the first capacitive coupling vary in
magnitude, thereby reducing alien crosstalk generated by the plug and
jack; positioning a second capacitive coupling including at least first
and second capacitive elements between the first and second wire pairs at
a second time delay from the first capacitive coupling, the second time
delay corresponding to an average time delay that optimizes near end
crosstalk; and positioning a third capacitive coupling a third time delay
away from the second capacitive coupling, such that the third time delay
is approximately the same as the first time delay.

17. The method of claim 16, wherein different time delays of the first
and second capacitive elements in the second capacitive coupling are
centered about the average time delay to optimize near end crosstalk and
are spaced apart to compensate for far end crosstalk

18. The method of claim 16, wherein the first and second zones of
compensation are placed across the 3-6 and 4-5 wire pairs within the
jack.

19. A telecommunications jack for use in a twisted pair system, the jack
comprising: a plurality of contact springs adapted to make electrical
contact with a plug when the plug is inserted into the jack; a plurality
of wire termination contacts for terminating wires to the jack; a
crosstalk compensation arrangement that provides crosstalk compensation
between elected tracks extending between the contact springs and the wire
termination contacts, the crosstalk compensation arrangement including a
first zone of compensation a first time delay away from the capacitive
coupling of the plug and a second zone of compensation at a second time
delay from the first zone of compensation, the second zone of
compensation having an average time delay that optimizes near end
crosstalk.

20. The telecommunications jack of claim 19, wherein the second zone of
compensation includes two capacitive elements spaced at different time
delays from the first zone of compensation to optimize far end crosstalk.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.
12/369,543, filed Feb. 11, 2009, which application claims the benefit of
provisional application Ser. No. 61/028,040, filed Feb. 12, 2008, which
applications are incorporated herein by reference in their entirety.

TECHNICAL FIELD

[0002] The present invention relates generally to telecommunications
equipment. More particularly, the present invention relates to
telecommunications jacks that are configured to compensate for near end
crosstalk and far end crosstalk.

BACKGROUND

[0003] In the field of data communications, communications networks
typically utilize techniques designed to maintain or improve the
integrity of signals being transmitted via the network ("transmission
signals"). To protect signal integrity, the communications networks
should, at a minimum, satisfy compliance standards that are established
by standards committees, such as the Institute of Electrical and
Electronics Engineers (IEEE). The compliance standards help network
designers provide communications networks that achieve at least minimum
levels of signal integrity as well as some standard of compatibility.

[0004] One prevalent type of communication system uses twisted pairs of
wires to transmit signals. In twisted pair systems, information such as
video, audio and data are transmitted in the form of balanced signals
over a pair of wires. The transmitted signal is defined by the voltage
difference between the wires.

[0005] Crosstalk can negatively affect signal integrity in twisted pair
systems. Crosstalk is unbalanced noise caused by capacitive and/or
inductive coupling between wires and a twisted pair system. Crosstalk can
exist in many variants, including near end crosstalk, far end crosstalk,
and alien crosstalk. Near end crosstalk refers to crosstalk detected at
the same end of a wire pair as the inductance causing it, while far end
crosstalk refers to crosstalk resulting from inductance at a far end of a
wire pair. Alien crosstalk refers to crosstalk that occurs between
different cables (i.e. different channels) in a bundle, rather than
between individual wires or circuits within a single cable. Alien
crosstalk can be introduced, for example, at a multiple connector
interface. With increasing data transmission speeds, increasing alien
crosstalk is generated among cables, and must be accounted for in
designing systems in which compensation for the crosstalk is applied. The
effects of all crosstalk become more difficult to address with increased
signal frequency ranges.

[0006] The effects of crosstalk also increase when transmission signals
are positioned closer to one another. Consequently, communications
networks include areas that are especially susceptible to crosstalk
because of the proximity of the transmission signals. In particular,
communications networks include connectors that bring transmission
signals in close proximity to one another. For example, the contacts of
traditional connectors (e.g., jacks and plugs) used to provide
interconnections in twisted pair telecommunications systems are
particularly susceptible to crosstalk interference. Furthermore, alien
crosstalk has been observed that could not be explained by the current
models which sum connectors and cable component results to calculate
channel results. This "excess" alien crosstalk is not compensated for in
existing designs.

[0007]FIG. 1 shows a prior art panel 20 adapted for use with a twisted
pair telecommunications system. The panel 20 includes a plurality of
jacks 22 placed in close proximity with one another. Each jack 22
includes a port 24 adapted to receive a standard telecommunications plug
26. Each of the jacks 22 is adapted to be terminated to four twisted
pairs of transmission wires. As shown at FIG. 2, each of the jacks 22
includes eight contact springs labeled as having positions 1-8. In use,
contact springs 4 and 5 are connected to a first pair of wires, the
contact springs 1 and 2 are connected to a second pair of wires, contact
springs 3 and 6 are connected to a third pair of wires, and contact
springs 7 and 8 are connected to a fourth pair of wires. As shown at FIG.
3, a typical plug 26 also has eight contacts (labeled 1-8) adapted to
interconnect with the corresponding eight contacts of the jack 22 when
the plug is inserted within the port 24.

[0008] To promote circuit density, the contacts of the jacks and the plugs
are required to be positioned in fairly close proximity to one another.
Thus, the contact regions of the jacks and plugs are particularly
susceptible to crosstalk. Furthermore, certain pairs of contacts are more
susceptible to crosstalk than others. For example, the first and third
pairs of contacts in the plugs and jacks are typically most susceptible
to crosstalk.

[0009] To address the problems of crosstalk, jacks have been designed with
contact spring configurations adapted to reduce the capacitive coupling
generated between the contact springs so that crosstalk is minimized. An
alternative approach involves intentionally generating crosstalk having a
magnitude and phase designed to compensate for or correct crosstalk
caused at the plug or jack. Typically, crosstalk compensation can be
provided by manipulating the positioning of the contacts or leads of the
jack or can be provided on a circuit board used to electrically connect
the contact springs of the jack to insulation displacement connectors of
the jack. The telecommunications industry is constantly striving toward
larger signal frequency ranges. As transmission frequency ranges widen,
crosstalk becomes more problematic. Thus, there is a need for further
development relating to crosstalk remediation.

SUMMARY

[0010] In accordance with the present disclosure, the above and other
problems are solved by the following.

[0011] In a first aspect, a method for providing crosstalk compensation in
a jack is disclosed. According to the method, the crosstalk compensation
is adapted to compensate for undesired crosstalk generated at a
capacitive coupling located at a plug inserted within the jack. The
method includes positioning a first capacitive coupling a first time
delay away from the capacitive coupling of the plug, the first capacitive
coupling having a greater magnitude and an opposite polarity as compared
to the capacitive coupling of the plug. The method also includes
positioning a second capacitive coupling at a second time delay from the
first capacitive coupling, the second time delay corresponding to an
average time delay that optimizes near end crosstalk. The second
capacitive coupling has generally the same overall magnitude but an
opposite polarity as compared to the first capacitive coupling, and
includes two capacitive elements spaced at different time delays from the
first capacitive coupling.

[0012] In a second aspect, a telecommunications jack is disclosed for use
in a twisted pair system. The jack includes a housing defining a port for
receiving a plug. The jack also includes a plurality of contact springs
adapted to make electrical contact with the plug when the plug is
inserted into the port of the housing. The jack includes a plurality of
wire termination contacts for terminating wires to the jack, and a
circuit board including conductive tracks that electrically connect the
contact springs to the wire termination contacts. The jack further
includes a crosstalk compensation arrangement that provides crosstalk
compensation between selected tracks of the circuit board. The crosstalk
compensation arrangement includes a first zone of compensation a first
time delay away from the capacitive coupling of the plug and a second
zone of compensation at an second time delay from the first zone of
compensation, the second zone of compensation including two capacitive
elements spaced at different time delays from the first zone of
compensation to optimize far end crosstalk and having an average time
delay that optimizes near end crosstalk.

[0013] In a third aspect, a crosstalk compensation system within a
telecommunications jack is disclosed. The crosstalk compensation system
includes a circuit board and a plurality of contact springs mounted on
the circuit board, the contact springs including first, second, third,
fourth, fifth, sixth, seventh and eighth consecutively arranged contact
springs. The crosstalk compensation system further includes a plurality
of wire termination contacts mounted on the circuit board, the wire
termination contents including first, second, third, fourth, fifth,
sixth, seventh and eighth wire termination contacts for terminating wires
to the jack, and a plurality of tracks on the circuit board, the tracks
including first, second, third, fourth, fifth, sixth, seventh and eighth
tracks that respectively electrically connect the first, second, third,
fourth, fifth, sixth, seventh and eighth contact springs to the first,
second, third, fourth, fifth, sixth, seventh and eighth wire termination
contacts. The crosstalk compensation system includes a crosstalk
compensation arrangement that provides crosstalk compensation between the
tracks of the circuit board. The crosstalk compensation arrangement
includes a first zone of compensation a first time delay away from the
contact springs and a second zone of compensation at an second time delay
from the first zone of compensation, the second zone of compensation
including two capacitive elements spaced at different time delays from
the first capacitive coupling and having an average time delay that that
optimizes near end crosstalk.

[0014] In a fourth aspect, a method for determining the positions of first
and second zones of crosstalk compensation in a jack is disclosed. The
method is directed to a jack in which the first and second zones of
crosstalk compensation are adapted to compensate for undesired crosstalk
caused by an undesired capacitive coupling located at a plug inserted
within the jack, the first zone of crosstalk compensation including a
first capacitive coupling positioned a first time delay away from the
undesired capacitive coupling of the plug, the first capacitive coupling
having a greater magnitude and an opposite polarity as compared to the
undesired capacitive coupling of the plug, the second zone of crosstalk
compensation including a second capacitive coupling having two capacitive
elements positioned, on average, a second time delay away from the first
capacitive coupling, the second capacitive coupling having generally the
same magnitude but an opposite polarity as compared to the first
capacitive coupling. The method includes positioning the first and second
capacitive couplings in initial positions in which the first and second
time delays are generally equal to one another. The method also includes
adjusting the position of the second capacitive coupling from the initial
position to an adjusted position to provide improved near end crosstalk
compensation. The method further includes adjusting the position of the
first and second capacitive elements to different lengths to provide
improved far end crosstalk compensation while maintaining the adjusted
position of the second capacitive coupling as the average position of the
first and second capacitive elements.

[0015] In a fifth aspect, a method of designing a crosstalk compensation
system for a telecommunications jack is disclosed. The method includes
positioning a first zone of crosstalk compensation across at least a
first wire pair and a second wire pair on a circuit board within a
telecommunications jack, the first zone of crosstalk compensation placed
at a first distance from contact springs associated with the first wire
pair and the second wire pair. The method also includes positioning a
second zone of crosstalk compensation across the at least first and
second wire pairs at a second distance from the first zone of crosstalk
compensation, the second zone of crosstalk compensation including a first
capacitive coupling and a second capacitive coupling. The method further
includes altering the position of the capacitive couplings to establish a
distance between the first capacitive coupling and the second capacitive
coupling while maintaining the second distance as an average distance
from the first zone of crosstalk compensation. Using the method
disclosed, altering the position of the capacitive couplings provides
improved far end crosstalk compensation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a perspective view of a prior art telecommunications
panel;

[0017] FIG. 2 is a schematic illustration of a prior art jack;

[0018] FIG. 3 is a schematic representation of a prior art
telecommunications plug;

[0019] FIG. 4 is a front, perspective view of a telecommunications jack
having features that are examples of inventive aspects in accordance with
the principles of the present disclosure;

[0021]FIG. 6 is a side view of the circuit board, insulation displacement
connectors and contact springs of the telecommunications jack of FIG. 4;

[0022]FIG. 7 is a front view of the circuit board, contact springs and
insulation displacement connectors of FIG. 6;

[0023]FIG. 8 is a top view of the circuit board and contact springs of
FIG. 6;

[0024]FIG. 9 is a cross-sectional view taken along section line 9-9 of
FIG. 8;

[0025] FIG. 10 is a schematic diagram showing a crosstalk compensation
scheme incorporated into the telecommunications jack of FIG. 4;

[0026] FIG. 11 is a schematic diagram showing a compensation arrangement
used to provide crosstalk compensation between the 4-5 and 3-6 pairs of
the telecommunications jack of FIG. 4;

[0027]FIG. 12 is a schematic vector diagram showing a compensation
arrangement used to provide crosstalk compensation between the 4-5 and
7-8 pairs of the telecommunications jack of FIG. 4;

[0028] FIG. 13 is a tracing overlay view of the circuit board used in the
telecommunications jack of FIG. 4;

[0029] FIG. 14 shows a front conductive layer of the circuit board used in
the telecommunications jack of FIG. 4;

[0030] FIG. 15 shows a middle conductive layer of the circuit board used
in the telecommunications jack of FIG. 4; and

[0031] FIG. 16 is shows a back conductive layer of the circuit board used
in the telecommunications jack of FIG. 4.

DETAILED DESCRIPTION

[0032] Various embodiments of the present disclosure will be described in
detail with reference to the drawings, wherein like reference numerals
represent like parts and assemblies throughout the several views.
Additionally, any examples set forth in this specification are not
intended to be limiting and merely set forth some of the many possible
embodiments for how aspects of the disclosure may be practiced.

[0033] In general, the present disclosure relates to methods and systems
for improving far end crosstalk compensation without adversely affecting
near end crosstalk compensation within a telecommunications jack. The
present disclosure generally describes crosstalk compensation schemes in
which near end and far end crosstalk are accounted for and compensated
against. In certain aspects, the crosstalk compensation is achieved by
use of at least two stages of capacitive compensation, in which the
second stage is placed at an average time delay from the first stage such
that near end crosstalk is optimized. The second stage has at least two
capacitive elements spaced at different time delays from the first
capacitive coupling to optimize far end crosstalk.

[0034] The present disclosure also relates to methods and systems for
compensating for alien crosstalk in a telecommunications jack. The
present disclosure describes crosstalk compensation schemes in which
alien crosstalk is compensated against, such as by selecting imbalanced
capacitive arrangements across wire pairs to reduce the overall crosstalk
experienced in a system, despite the potential for imbalanced
compensation between wire pairs within a single jack.

[0035] FIGS. 4 and 5 show a telecommunications jack 120 (i.e., a
telecommunications connector) having features that are examples of
inventive aspects in accordance with the principles of the present
disclosure. The jack 120 includes a dielectric housing 122 having a front
piece 124 and a rear piece 126. The front and rear pieces 124, 126 can be
interconnected by a snap fit connection. The front piece 124 defines a
front port 128 sized and shaped to receive a conventional
telecommunications plug (e.g., an RJ style plug such as an RJ 45 plug).
The rear piece 126 defines an insulation displacement connector interface
and includes a plurality of towers 130 adapted to house insulation
displacement connector blades/contacts. The jack 120 further includes a
circuit board 132 that mounts between the front and rear pieces 124, 126
of the housing 122. A plurality of contact springs CS1-CS8 are
terminated to a front side of the circuit board 132. A plurality of
insulation displacement connector blades IDC1-IDC8 are
terminated to a back side of the circuit board 132. The contact springs
CS1-CS8 extend into the front port 128 and are adapted to be
electrically connected to corresponding contacts provided on a plug when
the plug is inserted into the front port 128. The insulation displacement
connector blades IDC1-IDC8 fit within the towers 130 of the
rear piece 126 of the housing 122. The circuit board 132 has tracks
T1-T8 (e.g., tracings, see FIGS. 14-17) that respectively
electrically connect the contact springs CS1-CS8 to the
insulation displacement connector blades IDC1-IDC8.

[0036] In use, wires are electrically connected to the contact springs
CS1-CS8 by inserting the wires between pairs of the insulation
displacement connector blades IDC1-IDC8. When the wires are
inserted between pairs of the insulation displacement connector blades
IDC1-IDC8, the blades cut through the insulation of the wires
and make electrical contact with the center conductors of the wires. In
this way, the insulation displacement connector blades
IDC1-IDC8, which are electrically connected to the contact
springs CS1-CS8 by the tracks on the circuit board, provide an
efficient means for electrically connecting a twisted pair of wires to
the contact springs CS1-CS8 of the jack 120.

[0037] The contact springs CS1-CS8 are shown more clearly in
FIGS. 6-8. The relative positioning, shape and curvature of the contact
springs CS1-CS8 is preferably adapted to provide some initial
crosstalk compensation at the jack 120.

[0038] The circuit board 132 of the jack 120 is preferably a multiple
layer circuit board. For example, FIG. 9 shows the circuit board 132
including a first conductive layer 140, a second conductive layer 142 and
a third conductive layer 144. The first and second conductive layers 140,
142 are separated by a first dielectric layer 146. The second and third
conductive layers 142, 144 are separated by a second dielectric layer
148. The first conductive layer 140 is located at a front side of the
circuit board 132 and the third conductive layer 144 is located at a back
side of the circuit board 132. The contact springs CS1-CS8 are
mounted at the front side of the circuit board 132, while the insulation
displacement connector blades IDC1-IDC8 are mounted at the back
side of the circuit board 132. Vias extend through the first and second
dielectric layers 146, 148 to provide electrical connections between the
conductive layers 140, 142 and 144. The conductive layers 140, 142 and
144 are defined by electrically the conductive tracks T1-T8
(see FIGS. 14-17). The tracks T1-T8 are formed (e.g., etched or
otherwise provided) on the dielectric layers 146, 148.

[0039] The circuit board 132 preferably includes structures for
compensating for near end crosstalk that occurs at the jack/plug
interface. In certain embodiments, the structures for compensating for
near end crosstalk include capacitive couplings provided between the
first and second conductive layers 140, 142. In preferred embodiments,
the capacitive couplings are provided by sets of opposing, generally
parallel capacitive plates located at the first and second conductive
layers 140, 142. To increase the magnitude of the capacitive coupling
provided between the capacitive plates of the first and second conductive
layers 140, 142, it is desirable for the first dielectric layer 146 to be
relatively thin. For example, in certain embodiments the first dielectric
layer 146 can have a thickness t1 less than about 0.01 inches, or
less than about 0.0075 inches, or less than about 0.005 inches, or less
than 0.003 inches. In other embodiments, the thickness t1 can be in
the range of 0.001 inches to 0.003 inches or in the range of 0.001 inches
to 0.005 inches. In a preferred embodiment, the thickness t1 is
about 0.002 inches.

[0040] In certain embodiments, the first dielectric layer 146 can be made
of a material having a relatively low dielectric constant. As used
herein, dielectric constants are dielectric constants relative to air. In
certain embodiments, the dielectric constant of the first dielectric
layer 146 can be equal to or less than about 5. In other embodiments, the
dielectric constant of the first dielectric layer 146 can be less than or
equal to about 4 or less than or equal to about 3. An example material
for manufacturing the first dielectric layer 146 is a flame resistant 4
(FR-4) circuit board material. FR-4 circuit board material is a composite
of a resin epoxy reinforced with a woven fiberglass mat.

[0041] The second dielectric layer 148 is preferably configured to isolate
the third conductive layer 144 from the first and second conductive
layers 140, 142. The second dielectric layer 148 can have a different
thickness t2 than the thickness t1 of the first dielectric
layer 146. In certain embodiments, the second dielectric layer 148 is at
least 2.5 times thicker than the first dielectric layer 146 or at least
five times thicker than the first dielectric layer 146. In still other
embodiments, the second dielectric layer 148 is at least 10 times or at
least 20 times thicker than the first dielectric layer 146. In one
example embodiment, the thickness t2 of the second dielectric layer
148 is in the range of 0.050 inches to 0.055 inches. In another example
embodiment, the thickness t2 of the second dielectric layer 148 is
in the range of 0.040 inches to 0.050 inches.

[0042] The second dielectric layer 148 can also be manufactured of a
different material as compared to the first dielectric layer 146. In
certain embodiments, the second dielectric layer can have different
dielectric properties as compared to the first dielectric layer 146. For
example, in certain embodiments the first dielectric layer 146 can have a
dielectric constant that is greater (e.g., at least 1.5 times or at least
2 times greater) than the dielectric constant of the second dielectric
layer 148. In one example, the second dielectric layer 148 can be
manufactured of a material such as FR-4. Of course, it will be
appreciated that other materials could also be used.

[0043] The circuit board 132 includes a number of capacitive couplings
having magnitudes and locations adapted to compensate for near end
crosstalk and far end crosstalk. These forms of crosstalk are
particularly problematic between the 4-5 and 3-6 pairs. To compensate for
near end crosstalk between the 4-5 and 3-6 pairs, three interdependent
zones of compensation are used between tracks T4-5 and tracks
T3-6. As shown at FIG. 10, the three interdependent zones of
compensation include a first zone of compensation ZA1, a second zone
of compensation ZA2 and a third zone of compensation ZA3. The
first zone of compensation ZA1 includes a capacitive coupling C1
between track T3 and track T5, and a capacitive coupling C2
between track T4 and track T6. The second zone of compensation
ZA2 includes a capacitive coupling C3 between track T3 and
track T4, and a capacitive coupling C4 between track T5 and
track T6. The third zone of compensation ZA3 includes a
capacitive coupling C5 between track T3 and track T5, and a
capacitive coupling C6 between track T4 and track T6.

[0044] To compensate for far end crosstalk, the capacitive couplings C3
and C4 are spaced apart, such that the average distance between the zones
of compensation is as described below in FIG. 11, but the distances for
the C3 and C4 couplings differ. As shown, coupling C3 is placed closer to
the first zone of compensation ZA1 than coupling C4 while
maintaining the average position of the zone ZA2 such that the
distance between zones is as described below in FIG. 11.

[0045] In the embodiments shown in the present disclosure, the capacitive
couplings C1 and C2 are equal in magnitude and location, maintaining
symmetry across the pairs. However, in certain embodiments, capacitive
couplings C1 and C2 may be selected such that they differ in magnitude to
compensate for alien crosstalk including the "excess" crosstalk
previously mentioned, which is noted to be worst in the case of the 3-6
pair. Specifically, it was determined that changes to alien crosstalk can
be made, both positively and negatively, by purposefully modifying the
size of the compensating capacitors, causing them to become asymmetric in
size and coupling. For example, in certain embodiments, the magnitude of
capacitor C1 is greater than the magnitude of capacitor C2, which can
reduce the alien crosstalk generated at the 3-6 pair. It is observed
that, analogously to varying the magnitudes of C1 and C2, varying the
relative magnitudes of the capacitive couplings within a zone of
compensation in the compensation between the 4-5 and 3-6 pairs can
improve the alien crosstalk observed. This is understood to have the
effect of compensating for the overall plug and jack configuration, as
opposed to typical crosstalk compensation schemes which generally only
account for crosstalk generated in the jack. Additional details regarding
methods and configurations for compensating for alien crosstalk are
described below.

[0046] To address overall crosstalk between the 4-5 and 3-6 pairs, a
relatively large amount of capacitance is used. This large amount of
capacitance can cause the jack to have unacceptable levels of return
loss. Methods for addressing this return loss are addressed in U.S.
patent application Ser. No. 11/402,544, filed Apr. 11, 2006, now U.S.
Pat. No. 7,381,098, and entitled "TELECOMMUNICATIONS JACK WITH CROSSTALK
MULTI-ZONE CROSSTALK COMPENSATION AND METHOD FOR DESIGNING", which is
hereby incorporated by reference in its entirety.

[0047] FIG. 11 is a schematic diagram representative of the compensation
arrangement used to provide crosstalk compensation between the 4-5 and
3-6 pairs. As shown at FIG. 11, the compensation arrangement includes a
first vector 100, a second vector 102, a third vector 104, and a fourth
vector 106. The first vector 100 and the third vector 104 have positive
polarities, while the second vector 102 and the fourth vector 106 have
negative polarities. The first vector 100 has a magnitude of M and
corresponds to crosstalk introduced at the plug. The second vector 102
has a magnitude of about -3M and corresponds to the overall crosstalk
introduced at the first zone of crosstalk ZA1 generated by the board
and springs. The third vector 104 has a magnitude of about 3M and
corresponds to the overall crosstalk introduced at the second zone of
compensation ZA2. The fourth vector 106 has a magnitude of about -M
and corresponds to the overall crosstalk introduced at the third zone of
compensation ZA3. It will be appreciated that each vector is a lump
sum of the total crosstalk or crosstalk compensation provided at each
respective compensation zone, with the vectors being placed at the
centers or midpoints of the compensation zones.

[0048] In designing the compensation scheme of FIG. 11, a number of
factors are taken into consideration when determining the placement of
the compensation zones. One factor includes the need to accommodate
signal travel in both directions (i.e., in forward and reverse
directions) through the tracks on the circuit board. To accommodate
forward and reverse transmissions through the circuit board, the
compensation scheme preferably has a configuration with forward and
reverse symmetry. It is also desirable for the compensation scheme to
provide optimized compensation over a relatively wide range of
transmission frequencies. For example, in one embodiment, performance is
optimized for frequencies ranging from 1 MHz to 500 MHz. It is further
desirable for the compensation arrangement to take into consideration the
phase shifts that occur as a result of the time delays that take place as
signals travel between the zones of compensation.

[0049] To minimize the effect of phase shift in the compensation
arrangement, it is preferred for the second vector 102 to be positioned
as close as possible to the first vector 100. In FIG. 11, the time delay
between the first vector 100 and the second vector 102 is shown as x. In
one example embodiment, x can be about 100 picoseconds for a signal
having a transmission speed of 3×108 meters per second.

[0050] To maintain forward and reverse symmetry, it is preferred for the
time delay between the third vector 104 and the fourth vector 106 to be
approximately the same as the time delay between the first vector 100 and
the second vector 102. As shown in FIG. 11, the time delay between the
third and fourth vectors is depicted as x.

[0051] The time delay y between the second vector 102 and the third vector
104 is preferably selected to optimize the overall compensation effect of
the compensation scheme over a relatively wide range of frequencies. By
varying the time delay y between the second vector 102 and the third
vector 104, the phase angles of the first and second compensation zones
are varied thereby altering the amount of compensation provided at
different frequencies. In one example embodiment, to design the time
delay y, the time delay y is initially set with a value generally equal
to x (i.e., the time delay between the first vector 102 and the second
vector 104). The system is then tested or simulated to determine if an
acceptable level of compensation is provided across the entire signal
frequency range intended to be used. If the system meets the near end
crosstalk requirements with the value y set equal to x, then no further
adjustment of the value y is needed. If the compensation scheme fails the
near end crosstalk requirements at higher frequencies, the time delay y
can be shortened to improve performance at higher frequencies. If the
compensation scheme fails the near end crosstalk requirements at lower
frequencies, the time delay y can be increased to improve crosstalk
performance for lower frequencies. It will be appreciated that the time
delay y can be varied without altering forward and reverse symmetry.

[0052] It has been determined that when magnitudes of the second and third
vectors 102, 104 are respectively about -3M and about 3M, the distance y
is preferably greater than the distance x to provide optimized crosstalk
compensation. However, if the magnitudes of the vectors 102, 104 are
reduced below about -3M and about 3M (e.g., to approximately -2.7M and
2.7M), the distance y is preferably less than the distance x to provide
optimized crosstalk compensation.

[0053] Crosstalk can also be an issue between the 1-2 and 3-6 pairs.
Particularly, substantial crosstalk can be generated between track
T2 and track T3. As shown at FIG. 10, a three-zone compensation
arrangement is used to compensate for this crosstalk. The three-zone
compensation arrangement includes a first zone of compensation ZB1,
a second zone of compensation ZB2 and a third zone of compensation
ZB3. The first zone of compensation ZB1 includes a capacitive
coupling C7 between track T1 and track T3, and a capacitive
coupling C8 between track T2 and track T6. The second zone of
compensation ZB2 includes a capacitive coupling C9 between track
T1 and track T6. The third zone of compensation ZB3
includes a capacitive coupling C10 between track T1 and track
T3. The three zones of compensation between the 1-2 and 3-6 pairs
can be placed at locations consistent with the vector diagram shown in
FIG. 11, described above.

[0054] In general, it has been determined that varying the relative
compensation among the pairs at the primary zones of compensation for
each pair can affect alien crosstalk. Regarding the zone of compensation
ZB1, it has been determined that varying the relative magnitudes of
the capacitive couplings C7 and C8, such that the capacitive couplings
are non-equal, can improve overall alien crosstalk of the plug and jack
system. In the embodiment shown, a larger capacitance is used for
capacitance C7 than C8, with the overall capacitance relating to the
capacitive coupling introduced at the plug, as described above in
conjunction with FIG. 11.

[0055] In general, it has been determined that in zone of compensation
ZB2 performance is optimized without use of a capacitive coupling
between track T2 and track T3. However, in certain embodiments,
such a capacitive coupling can be included to preserve symmetry between
the pairs. Likewise, in zone ZB3, no capacitive coupling is included
between track T2 and track T6, although in symmetric systems
such a coupling could be included. Furthermore, it will be appreciated
that the magnitudes of the compensation between the 3-6 and 4-5 pairs are
substantially greater in magnitude than those between the 1-2 and 3-6
pairs.

[0056] Additional crosstalk exists between the 4-5 and 7-8 pairs. In the
embodiment of the crosstalk compensation arrangement shown in FIG. 10, a
two zone arrangement is used to compensate for crosstalk between those
pairs. As shown, the compensation arrangement between the 4-5 and 7-8
pairs is a two zone compensation including a capacitive coupling C11 in a
first zone Zci provided between track T5 and track Tg, and
capacitive coupling C12 in a second zone Z2 provided between track
T4 and track Tg.

[0057]FIG. 12 is a schematic vector diagram showing the compensation
arrangement used between the 4-5 and 7-8 pairs. As shown at FIG. 12,
three crosstalk vectors are taken into consideration. The first crosstalk
vector 110 is representative of crosstalk generated at the plug. A second
vector 112 is representative of crosstalk provided at the first
compensation zone ZC1. The third vector 114 is representative of
crosstalk generated at the second compensation zone Z2. The first
and third vectors 110, 114 have positive polarities and magnitudes of
about N. The second vector 112 has a negative polarity and a magnitude
about 2N. Although the disclosed compensation arrangement is asymmetric
among the pairs, a symmetric arrangement could be provided as well.
Furthermore, it will be appreciated that M (shown at FIG. 11) is
typically substantially greater in magnitude than N (shown at FIG. 12).

[0058] As described above, varying the capacitive values across the 4-5
and 7-8 wire pairs used in the first zone of compensation Zci can
improve alien crosstalk values generated from the plug-jack system. In
the embodiment shown, a completely unbalanced configuration is selected,
such that Zci includes only compensation between track T5 and
track T8, with no corresponding balanced compensation between tracks
T4 and T7. In further embodiments, a different, unbalanced
arrangement may be selected.

[0059] In addition to the multiple zone compensation arrangements
described above, a number of single zone compensations can also be used.
For example, zone ZD1 is a single zone compensation used to
compensate for crosstalk generated between the 1-2 and 4-5 pairs, and
includes a capacitive coupling C13 provided between track T2 and
track T5. Another single zone compensation ZE1 compensates for
crosstalk generated between the 3-6 and 7-8 pairs, and is provided by a
capacitive coupling C14 formed between track T3 and track T7.
Other capacitive couplings may be included which compensate for
unintended crosstalk generated within the board itself.

[0060] Again, each of the single zone compensations is illustrated as
using an unbalanced arrangement to account for alien crosstalk generated
by the plug and jack. It is observed that the "excess" alien crosstalk
may be caused, at least in part, by an imbalance in connecting hardware
contributing to excess crosstalk between the cables, particularly in
short sections of cable between connectors. Therefore, imbalanced
compensation across wire pairs can compensate for this excess crosstalk.
In the embodiment shown, zone ZD1 includes only compensation C13
between track T2 and track T5, but no compensation between
tracks track T1 and track T4. Similarly, zone ZE1 includes
only compensation C14 between track T3 and track T7, but no
compensation between tracks track T6 and track T8.

[0061] The crosstalk compensation schemes illustrated herein generally are
accomplished by first positioning a crosstalk compensation arrangement
relating to crosstalk within the plug and jack, across a variety of wire
pairs. In designing the multi-zone crosstalk compensation schemes in
accordance with this disclosure, a designer will generally first locate a
first zone of capacitive coupling a first time delay away from the
capacitive coupling at the plug. The designer can then position a second
capacitive coupling, i.e. a second zone of compensation, at a second time
delay away from the first time delay. That second zone of compensation
can be made up of more than one capacitive coupling, and can have
capacitive couplings of differing magnitude. For example, two capacitors
can make up a zone of compensation, and can be placed at differing
distances from a first zone. An example of such a configuration is
illustrated by zone ZA2 as described above.

[0062] Once crosstalk for the plug and jack have been brought to an
acceptable level using the techniques described above, the compensation
arrangement can be altered to improve alien crosstalk. Altering the
compensation arrangement is performed to accommodate one or more zones of
crosstalk compensation having an asymmetric capacitive coupling between a
wire pairs, such that alien crosstalk is reduced. This can be performed
by changing the relative magnitudes of the capacitive couplings between
wire pairs in one or more of the zones of compensation. In certain
embodiments, a designer can start with a compensation arrangement having
symmetric capacitive couplings across complementary wire pairs (e.g. from
the 3-6 pair to the 4-5 pair, having equal couplings between T3 and
T5 and between T4 and T6).

[0063] The various capacitive couplings illustrated in the present
disclosure provide an example design for which far end and alien
crosstalk are addressed. Additional embodiments exist in which these
types of crosstalk are compensated for. In the various embodiments, any
amount of asymmetry in any zone of compensation can be introduced to
compensate for alien crosstalk, from complete symmetry to complete
asymmetry.

[0064] In general, the various asymmetric capacitive coupling selections
made to account for alien crosstalk are believed to, as a whole,
compensate for crosstalk generated in an overall system including both a
plug and a contact set of a modular jack, as described above in FIGS.
4-7. It is particularly notable that the crosstalk compensations selected
in the present disclosure may not be symmetric in the sense that equal
capacitive couplings are not applied across complementary tracks of a
wire pair. Although this may have the effect of slightly worse
performance with respect to connector balance and crosstalk within the
pair, the net effect of a number of plug and jack systems in close
proximity is an improved overall crosstalk compensation.

[0065] FIGS. 13-16 show an example circuit board layout for implementing
the compensation arrangement of FIG. 10. FIGS. 14-16 respectively show
the front, middle and back conductive layers 140, 142 and 144 of the
circuit board 132. FIG. 13 is an overlay of the three conductive layers
140, 142 and 144. The circuit board 132 defines openings 301-308 that
respectively receive posts of the contact springs CS1-CS8 so
that the contact springs CS1-CS8 are terminated to the board
132. The circuit board also defines openings 401-408 for respectively
receiving posts of the insulation displacement connector blades
IDC1-IDC8 such that the insulation displacement connector
blades IDC1-IDC8 are terminated to the circuit board. Vias
extend through the circuit board for electrically interconnecting the
tracks between the layers 140, 142 and 144, and to the various capacitive
couplings C1-C13. For example, vias V4A and V4B interconnect
the portions of the track T4 located at the different layers 140,
142 and 144 to the capacitive couplings C3 and C6. Also, via V5,
interconnects the portions of the track T5 located at the different
layers 140, 142 and 144 to capacitive coupling C5. Moreover, via V6
interconnects the portions of the track T6 located at the different
layers 140, 142 and 144 with capacitive coupling C6. Likewise, via
V3 interconnects the portions of the track T3 located at the
different layers 140, 142 and 144 to capacitive coupling C5.

[0066] Referring to FIGS. 14-16, the capacitive coupling C1 of the first
zone of compensation ZA1 is provided by opposing capacitor plates
C15 and C13 respectively provided at layers 142 and 144. The
capacitive coupling C2 of the first zone of compensation ZA1 is
provided by opposing capacitor plates C24 and C26 that are
respectively provided at the layers 142 and 144. The capacitive coupling
C3 of the second compensation zone ZA2 is provided by opposing
capacitor plates C34 and C33 that are respectively provided at
layers 142 and 144. The capacitive coupling C4 of the second compensation
zone ZA2 is provided by opposing capacitor plates C46 and
C45 that are respectively provided at layers 142 and 144. The
capacitive coupling C5 of the third compensation zone ZA3 is
provided by a capacitor plate C55A that is provided at layer 142.
The capacitive coupling C5 is also provided by inter-digitated capacitor
fingers C55B and C53B that are provided at layer 140. The
capacitive coupling C6 of the second compensation zone ZA3 is
provided by capacitor plate C66A provided at layer 142. The
capacitive coupling C6 is also provided by inter-digitated capacitor
fingers C66B and C64B provided at layer 140.

[0067] The capacitive coupling C7 of the first compensation zone ZB1
is provided by opposing capacitor plates C71 and C73 that are
respectively provided at layers 142 and 144 of the circuit board. The
capacitive coupling C8 of the first compensation zone ZB1 is
provided by opposing capacitor plates C82 and C86 that are
respectively provided at the layers 142 and 144 of the circuit board. The
capacitive coupling C9 of the second zone of compensation ZB2 is
provided by opposing capacitor plates C91 and C96 that are
respectively provided at layer 142 and 144 of the circuit board. The
capacitive coupling C10 of the third zone of compensation ZB3 is
provided by opposing capacitor plates C101 and C103 that are
respectively provided at layers 142 and 144 of the circuit board.

[0068] The capacitive coupling C11 of the first compensation zone ZC1
is provided by opposing capacitor plates C115 and C118 that are
respectively provided at layers 142 and 144 of the circuit board. The
capacitive coupling C12 of the second compensation zone ZC2 is provided
by adjacent leads C124 and C128, respectively, located at layer 142. The
capacitive coupling C13 of the zone of compensation ZD1 is provided
by opposing capacitor plates C132 and C135 provided at layers
142 and 144 of the circuit board. The capacitive coupling C14 of the zone
of compensation ZE1 is provided by opposing capacitor plates
C147 and C143 respectively provided at layers 142 and 144 of
the circuit board.

[0069] Various manufacturing and routing techniques may be implemented in
the placement of the tracks, vias, and capacitors described herein.
Additional details regarding the routing and placement of circuit
components are described in U.S. patent application Ser. No. 11/402,544,
filed Apr. 11, 2006, now U.S. Pat. No. 7,381,098, which was previously
incorporated by reference in its entirety.

[0070] The above specification, examples and data provide a complete
description of the manufacture and use of the composition of the
invention. Since many embodiments of the invention can be made without
departing from the spirit and scope of the invention, the invention
resides in the claims hereinafter appended.